Organic light emitting diode lighting systems

ABSTRACT

A lighting system includes a plurality of organic light emitting diode (OLED) devices. By selecting the plurality of OLED devices, or by selectively controlling the plurality of OLED devices, the color characteristics of the lighting system can be tuned. The lifetime of the lighting system can be improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/090,150, filed on Aug. 19, 2008, and U.S. Provisional PatentApplication No. 61/102,326, filed on Oct. 2, 2008, the completedisclosures of both applications being hereby incorporated by referencein their entirety.

BACKGROUND

Organic light emitting diodes (OLEDs) can utilize organic smallmolecules or polymers that produce light when transferred into theirexcited state by an external power source. Accordingly, OLED devices maybe referred to as polymer light emitting diode (PLED) devices or smallmolecule organic light emitting diode (SMOLED) devices depending ontheir active compositions. Depending on the driven mechanisms of theOLEDs, sometimes the terminologies of active matrix OLED (AMOLED) andpassive matrix OLED (PMOLED) are used.

Earlier OLEDs were typically based on relatively simple structures,where a thin layer of the electroluminescence (EL) conjugated polymerwas enclosed between a pair of electrodes. When a voltage is applied tothe electrodes, the positive (anode) and the negative (cathode)electrodes can provide injection of holes and electrons, respectively,into the EL polymer. In the EL polymer layer, electrons and holes movetowards each other in the applied electrical field and form excitons,which are bound excited states that can relax down into the ground stateradiatively by emitting a photon. This process can be referred to aselectroluminescence. OLED devices are of interest in, for example,display, signage, and lighting.

OLEDs were first designed in the 1980s, see, e.g., C. W. Tang, S. A. VanSlyke, Organic electroluminescent diodes, Appl. Phys. Lett. 1987, 51,913. More recent developments in OLED materials and applications aregenerally described in Kraft et al., Angew. Chem. Int. Ed., 1998, 37,402-428, and Z., Li and H. Meng, Organic Light-Emitting Materials andDevices (Optical Science and Engineering Series), CRC Taylor & Francis(Sep. 12, 2006). The disclosures of these references are incorporated byreference in their entirety.

SUMMARY

Described herein are embodiments which include, among other things,devices, articles, instruments, apparatuses, kits, systems, and thelike, and methods of making and methods of using same. Morespecifically, the various embodiments described in this applicationgenerally relate to lighting emitting systems comprising light emittingdiode (LED) devices. In particular, the embodiments are related to theuse of organic light emitting diodes (OLED) in lighting systems.

In one aspect, a lighting system is provided including a plurality ofOLED devices, and a controller configured to selectively drive at leastsome of the plurality of OLED devices at different activation levels.The controller may be configured to selectively drive the OLED devicesto different activation levels to increase a lifetime of the lightingsystem. In another aspect, the controller may be configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristic. At least one of the plurality of OLED devices has atleast one coupler configured to electrically couple the OLED device to apower supply and an encapsulation that isolates the OLED device from anambient environment.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices, wherein each of the plurality of OLEDdevices has an active region. In this aspect, at least some of the OLEDdevices have active regions of different sizes, and the different sizesare selected such that light emitted from the lighting system hasdesired color characteristics. In this aspect, OLED devices havingactive regions of different sizes have substantially matching lifetimes.

In another aspect, a method is provided comprising selectivelycontrolling activation levels of at least some of a plurality of OLEDdevices in a lighting system to improve a lifetime of the lightingsystem.

In another embodiment, the method includes selecting a subset of OLEDdevices from a plurality of pre-manufactured modular OLED devices andcoupling the selected subset of OLED devices to a mount. The subset ofOLED devices is selected to have a mixed output light spectrum withdesired color characteristics.

In another embodiment, a kit is provided. The kit has a plurality ofOLED devices and a plurality of couplers. At least one of the pluralityof couplers is configured to electrically couple at least one of theplurality of OLED devices to a power supply.

At least one advantage from at least one embodiment is that the OLEDlighting system can have easily tunable color characteristics. This canbe achieved in a “low cost” approach by replacing the individual OLEDdevices, or in a more flexible approach by selectively controlling theOLED devices using a controller.

At least another advantage from at least one embodiment is that thelifetime of the lighting system can be improved. This can be achieved,for example, by replacing individual OLED devices, providing redundancy,or selectively controlling the OLED devices using a controller for wearleveling.

BRIEF DESCRIPTION OF FIGURES

FIG. 1A is a perspective view of an example OLED device implemented inan example lighting system;

FIG. 1B is a block diagram of an example controller for controlling thelighting system;

FIGS. 2A-2D are perspective views of example OLED device couplers;

FIG. 3 is a cross-sectional view of an example OLED device packaged inan encapsulation;

FIG. 4 is a cross-sectional view of a plurality of packaged OLED devicestightly arranged on a curved surface;

FIG. 5A is a top plan view of a plurality hexagonal OLED devices tightlyarranged into a matrix;

FIG. 5B illustrates example voltage drive pulses for redundant blue OLEDdevices;

FIG. 5C illustrates example voltage drive pulses including reversebiases for healing OLED devices;

FIG. 5D is a schematic diagram illustrating address swapping among OLEDdevices for wear leveling;

FIG. 6 illustrates example emission spectra of individual OLED devicesand the mixed output spectrum;

FIG. 7 is a schematic diagram illustrating an example lighting systemincluding OLED devices of different sizes;

FIG. 8 is an exploded view of a stacked OLED device assembled from a kitof pre-manufactured, modular OLED devices;

FIGS. 9A-9C are cross-sectional views of example elongated conductorsused for coupling OLED devices to form an OLED lighting system; and

FIG. 9D is a schematic diagram illustrating OLED devices being coupledusing elongated conductors.

DETAILED DESCRIPTION

Introduction

All references cited in this application are hereby incorporated byreference in their entirety. In particular, the disclosures of U.S.Provisional Patent Application No. 61/090,150, filed on Aug. 19, 2008,and U.S. Provisional Patent Application No. 61/102,326, filed on Oct. 2,2008, are hereby incorporated by reference in their entirety.

The use of organic materials in electroluminescent devices offersseveral desirable properties, for example, increased luminescence of thedevice; lower threshold voltage; ease of processability of materials andcomponents during device fabrication; the ability to use spin casting,drop casting, and printing techniques to apply different layers inelectroluminescent devices; the ability to prepare flexibleelectroluminescent devices; the ability to prepare low-weightelectroluminescent devices; and the ability to prepare low-costelectroluminescent devices.

An electroluminescent device generally can be a device that convertselectrical current to electromagnetic radiation. In particular, OLEDsprovide an efficient way to produce light at low voltage and minimalradiant heat. These devices currently find uses in many consumerelectronics such as displays, signage, and lighting. OLEDs are generallyknown in the art as described in, for example, Organic Light-EmittingMaterials and Devices, edited by Li and Meng, 2007.

Lighting System

An example lighting system 10 is illustrated in FIG. 1A. The lightingsystem 10 comprises a plurality of OLED devices 100. The plurality ofOLED devices are selected such that the lighting system 10 emits lightwith a predetermined color characteristic. A desired colorcharacteristic can be one of a color temperature or a color renderingindex. For example, by selectively mixing OLED devices of differentcolors, the light output from the light emitting system 10 can besubstantially white. In addition, the light output from the lightemitting system 10 can be tunable based on user preferences. Thus, thelighting system 10 is a configurable system.

In one embodiment, at least some of the OLED devices emit light ofdifferent colors, and wherein the colors are selected from, for example,red, green, blue, white, and the like. In this application, the phrase“at least some” of the OLED devices refers to two or more OLED devices.At least one of the OLED devices is removable, and the system is alsoexpandable to have more OLED devices “plugged in.” Thus, the color ofthe output light from the lighting system, which is a mix of those ofindividual OLED devices, is changeable by selectively replacing at leasta subset of OLED devices.

OLED Devices

An example OLED device 100 is illustrated in FIG. 1A as part of alighting system 10. The OLED device 100 can comprise a substrate 102, ananode 104, a cathode 106, and an active region 108. An inverted OLEDstructure can also be used. For example, a bottom cathode can bedisposed over a substrate, followed by an active region and anode.

The active region 108 comprises an organic material, and is electricallycoupled to the anode 104 and the cathode 106. The active region 108 isconfigured to emit a broadband emission spectrum with a full width athalf maximum (FWHM) larger than about 50 nm.

The OLED device 100 can have a plurality of couplers 112 configured tocouple the OLED device 100 to a mount 119 through indentations 113. Thecouplers 112 can be mechanical couplers, or can be used to electricallycouple at least one of the anode 104 or the cathode 106 to a powersupply 114. In one embodiment, the couplers 112 are used for bothelectrical coupling and mechanical coupling.

In some embodiments, OLED device 100 a can be provided having one ormore indentations 113 a, and the mount 119 can have attached couplers112 a configured to couple the OLED device 100 a to the mount 119. Asdescribed further below, in some other embodiments, standalone couplerscan be provided to couple the OLED devices with a mount or with eachother.

The OLED device 100 also can have an encapsulation 116 that isolates theactive region 108 from an ambient environment. In particular, theencapsulation 116 prevents water vapor and oxygen from entering theenclosure 118 to interact with the organic material in the active region108. With the couplers 112 and the encapsulation 116, the OLED device100 may be readily used as a standalone device, or may be dropped in alighting system to replace another device.

The couplers 112 may be configured to electrically couple at least oneof the anode 104 or the cathode 106 with the power supply 114 via amount 119. The mount 119 is sometimes referred to as the “systemsubstrate,” which provides a frame onto which the lighting system can bebuilt. In addition to mechanical support, the mount 119 can also provideelectrical paths for the OLED devices. The mount 119 may be flat orcurved. The mount 119 can be flexible, and the resulting lighting systemcan be flexible in shape. The mount 119 may comprise one or more railsto which OLED devices are slidably coupled.

Some of the couplers 112 may be configured to electrically couple atleast one of the anode 104 or the cathode 106 with the power supply 114via a second OLED device 120. By selecting a plurality of OLED devices,a lighting system may be assembled with a desired color, pattern, area,and brightness.

In addition to the electrical coupling, the couplers 112 may alsomechanically couple the OLED device with the mount 119 or with thesecond OLED device 120.

The mount may be configured to be free-standing, ceiling mounted, orwall mounted. Since OLEDs are Lambertian emitters, the mount needs notbe designed to mix the light of OLEDs of various emission spectra.

Substrate

Substrates are generally known in the art. Descriptions of varioussubstrates may be found in, for example, Z., Li and H. Meng, OrganicLight-Emitting Materials and Devices (Optical Science and EngineeringSeries). The substrate 102 of the OLED device 100 can be, for example, asolid substrate or a flexible substrate. The substrate can comprise, forexample, an inorganic material or an organic material. The substrate canbe, for example, made from glass, metal foil, or plastic. The substratecan be, for example, flats or can have a curvature in one or moredimensions. The substrate can be, for example, rigid, flexible orconformable. The substrate can be, for example, transparent,semi-transparent, translucent, or opaque.

Anode

Anodes are generally known in the art. The anode 104 of the OLED device100 can be transparent to the light emitted from the OLED device 100.The anode 104 may comprise, for example, a transparent conductive oxide(TCO). Examples of TCOs include indium tin oxide (ITO), ZnO, and thelike. ITO in the form of thin layers (e.g., about 100 nm thick) issubstantially transparent to visible light. Substantially transparentlayers desirably allow a visible light transmission of about 70% ormore. ITO has a relatively high work function that helps the injectionof holes into the active region 108. The ITO may be coated on a glass orplastic substrate.

In some other embodiments, anodes can be thin and somewhat transparent,or comprise thick and highly reflective metal.

Cathode

Cathodes are generally known in the art. The cathode 106 of the OLEDdevice 100 can also be transparent. The cathode 106 may comprise, forexample, a thin metal film such as aluminum or calcium, or a non-metalconductive layer. The cathode 106 typically has a relatively low workfunction to help injecting electrons into the active region 108. Thecathode 106 can be at least 100-200 nm thick.

Active Region

The active region refers generally to the region where electrons andholes recombine to radiate photons. In the claimed embodiments, theactive region comprises an organic material, and the radiative photonenergy may correspond to the energy difference between the lowestunoccupied molecular orbital (LUMO) level and the highest occupiedmolecular orbital (HOMO) level of the organic material. Photons of lowerenergy/longer wavelength may be generated by higher-energy photonsthrough fluorescent or phosphorescent processes.

The active region can comprise multiple layers, for example, acombination of p- and n-type layers. The p- and n-type materials may bebonded to each other. The bonding can be ionic or covalent bonding. Themultiple layers of the active region may form heterostructurestherebetween.

The active region may be manufactured by known methods including, forexample, spin casting, drop casting, slot die coating, vapor depositionor sputtering, crystalline growth, patterned etching, dip coating, or byprinting techniques such as ink jet printing, off-setting, transferprocesses, or by spray applications.

Organic Material

The organic material in the active region 108 may include anelectroluminescent polymer. The polymer may be a fluorescent emitter, ora phosphorescent emitter or a combination of fluorescent andphosphorescent emitters. The polymer may include, for example,poly-phenylene vinylene, or polyfluorene. The polymers are oftenengineered to substitute side chains onto the backbone to tune the coloror to improve the processing of the polymers.

Alternative to a polymer emitter, a small molecule emitter comprisingfor example, organo-metallic chelates or conjugated dendrimers, may beused.

The organic material may be doped with phosphorescent materials.

Electrical Coupling

The electrical coupling between the active region 108 and the anode 104or cathode 106 may be a direct-contact coupling, or through more layersas discussed in detail below.

Power Supply

The power supply 114 may comprise a battery, an adapter, or may be partof a power grid. The OLED devices may be powered by AC or DC current.

Feedback

A feedback mechanism may be provided for a controller 130 to control thelighting system 10 or the OLED devices 120. The feedback mechanism mayinclude, for example, a sensor 140 for sensing a luminance of one ormore of the OLED devices. The output from the sensor 140 is then fedback to the controller 130. Based on the feedback, the controller 130may control the drive current or drive voltage of individual OLEDdevices or the lighting system 10 to adjust a color or a luminance oflight emission, or some other characteristic of the output light.Although a feedback data line 142 in the form of a wire is shown totransmit feedback data from the sensor 140 to the controller 130, thoseof ordinary skill in the art will recognize that wireless transmissionmay be used.

In addition to the remote sensor 140 shown in FIG. 1A, one or moresensors may be located adjacent to individual OLED devices to measure,for example, a measured current, a capacitance or a junctiontemperature. These parameters can also be fed back to the controller 130to control the lighting system 10.

Controller

The lighting system 10 may comprise the controller 130. The controller130 may include a processor and memory. Each of the individual OLEDdevices may be assigned a logical address, and the control circuitindividually controls the OLED devices based on their logical addresses.The controller 130 may individually address and control the OLED devicesto adjust the color, pattern, brightness, or to compensate for aging.

Instead of changing the output color of the lighting system 10 byselectively coupling different OLED devices 120 onto the mount 119 asdiscussed above, a color of the emitted light from the lighting systemcan also be tunable by selectively driving at least one of the pluralityof OLED devices differently from other OLED devices.

Selectively driving some of the plurality of OLED devices differentlyfrom other OLED devices may be realized by, for example, selectivelyvarying a drive voltage or a drive current of the OLED devices.

A simplified block diagram of a controller 130 according to oneembodiment is shown in FIG. 1B. As shown, the plurality of OLED devices120 a, 120 b, 120 c can be controlled by the controller 130 throughdigital-to-analog converters (DAC) 150 a, 150 b, and 150 c,respectively. The OLED devices 120 a, 120 b, 120 c can have differentcolors, such as red, green, and blue, respectively. The DAC 150 a, 150b, 150 c can deliver drive current pulses of suitable amplitudes andwidths to their respective OLED devices 120 a, 120 b, and 120 c. TheOLED devices 120 a, 120 b, 120 c can be driven independently,collectively, or interdependently.

The controller 130 can further comprise an input/output (I/O) interface152 to receive the feedback data from the sensor 140 through thefeedback data line 142. Memory 154 can be included in the controller 130to store commands to generate drive sequences. A clock 155 can be usedto synchronize the drive sequences. The controller 130 can furthercomprise a data port 156 to receive command data from data line 158, andthe command data can come from a user, a processor, or a computer. Thecontroller 130 can further comprise other components generally known inthe art, such as shift registers.

The controller 130 can be implemented using, for example, a computerwith suitable control software and additional discrete components, orusing an application specific integrated circuit (ASIC).

Coupler

The OLED device in accordance with the claimed embodiments may comprisea coupler for coupling the OLED device with a mount or with one or moreother OLED devices. The resulting OLED device is pre-manufactured in amodular fashion such that the OLED device may be a “plug-and-play”device. The OLED device can be readily “plugged in” to a system toreconfigure the color, appearance, brightness, or other properties ofthe system, or replace an existing OLED device in the system. Thecoupler can provide mechanical or electrical coupling. In addition, thecoupler can provide a combination of electrical and mechanical coupling.

In the embodiment shown in FIG. 1A, the couplers 112 include those forcoupling the OLED device 100 onto a mount 119, and those that can beconfigured to couple to one or more other OLED devices.

In one embodiment as illustrated in FIG. 2A, a coupler 200 a maycomprise a plurality of protrusions 202 configured to couple to acomplementary opening or indentation 204 in a corresponding coupler 200b. The lateral dimension of the opening 204 substantially matches thespacing of the protrusions 202. The indentations may be holes or slotsin the OLED device. The protrusions 202, or the coupler 200 b, or both,may be slightly flexible. This can be achieved, for example, by makingthe couplers 200 a and 200 b using plastics. By plugging the protrusions202 into the opening 204, a removable yet stable, coupling can berealized. The interlocking mechanism resembles that of the LEGO™building blocks. The corresponding coupler 200 b may be part of themount, or part of a second OLED device. The protrusions 202 may haveconductive and/or insulating patterns 203 disposed thereon, which may beelectrically coupled to corresponding conductive regions (not shown) inthe indentations 204 to make electrical connections when the couplers200 a, 200 b are joined together. These conductive regions may beelectrically connected to at least one of the anode or cathode or apower supply. The conductive regions of the couplers may be configuredto provide an electrical connection between the OLED device electrodesand a power supply when corresponding couplers are joined.

In one embodiment as illustrated in FIG. 2B, a coupler 201 a maycomprise one or more protrusions 206 configured to be coupled intocorresponding indentations 208 in a corresponding coupler 201 b. Theprotrusions 206 may have conductive patterns 209 disposed thereon, whichmay be electrically coupled to corresponding conductive regions (notshown) in the indentations 208 to make electrical connections when thecouplers 201 a, 201 b are joined together. Thus, in addition to makingthe mechanical coupling, the couplers also function as electricalcoupling.

In one embodiment as illustrated in FIG. 2C, a plurality ofsubstantially identical OLED devices 220, 222 can be matingly coupledusing matching couplers 224, 226. For example, the outer diameter of thecoupler 224 may be substantially the same as the inner aperture of thecoupler 226, such that the coupler 224 may be snugly fit into thecoupler 226. A large number of OLED devices can thus be coupled,mechanically and/or electrically, to form a lighting system.

In another embodiment as illustrated in FIG. 2D, an OLED device 230 hasprotrusion portion 232 and indentation portion 234 fitted with metalinserts 236, 238, respectively. The metal inserts 236, 238 can becoupled to the electrodes of the OLED device 230. Identical OLED devicescan thus be matingly coupled to each other while the metal inserts 236,238 form electrical connections. The metal inserts 236, 238 can bespring loaded to facilitate the mechanical coupling.

In the embodiments shown in FIGS. 1A-2D, the couplers are attached to,or are part of, the OLED devices. As discussed below, in some otherembodiments, couplers may be provided separately from the OLED devicesand may be provided as part of a kit for assembling OLED devices into alighting system.

Encapsulation

The OLED device may be already packaged in an encapsulation thatprotects the organic material of the OLED device from the ambientenvironment. The resulting OLED device may thus be a standalone devicethat can be readily installed in a system which does not necessarilyprovide oxygen and water vapor barriers.

Encapsulation may comprise barrier layers such as single or multi-layerbarrier films such as Barix. Methods of coverage may include lamination,vapor deposition, or solution deposition. Furthermore, the encapsulationmay comprise a sealant and a barrier structure such as a barrier film orhousing. Desiccant materials may be contained within the encapsulation.

An encapsulation 302 of an OLED device 300 is illustrated in FIG. 3. Theencapsulation 302 comprises a housing 304 forming an enclosure 306 withthe substrate 308. A first sealant 310 is disposed between the housing304 and the substrate 308, and forms an oxygen and water vapor barrierfor the active region 312. The first sealant comprises, for example,Mylar™ coated with metal.

The housing may have a first electrically conductive path 314 disposedin a first hermetic seal 316 through the housing 304. The firstelectrically conductive path 314 may be electrically coupled to thecathode 318.

The housing 304 may further have a second electrically conductive path320 through the housing 304 via a second hermetic seal 324. The secondelectrically conductive path 320 may be electrically coupled to theanode 322. In this case, the housing 304 may comprise a non-conductivematerial.

In another embodiment, the housing 304 may be electrically conductive.For example, the housing 304 may comprise a metal, such as aluminum, ora conductive plastic. In this case, the first electrically conductivepath 314 is electrically isolated from the housing 304. Instead of usingthe second electrically conductive path 320 through the housing 304, theanode 322 may be electrically coupled to the housing 304 through thefirst sealant 310 which in this case is conductive.

The electrically conductive housing 304 may thus form a common anodewith neighboring OLED devices.

Housing

As shown in FIG. 4, the housing 400 has a contoured shape that allowsthe OLED device 402 to be arranged on a curved surface 404 with aplurality of neighboring OLED devices 406, 408 without causingsubstantial interference between housings of neighboring OLED devices.

In one embodiment, the housing 400 has a slanted side wall 410 and abottom wall 412, and wherein a slant angle α of the slanted side wall410 is selected such that, when the OLED device 402 is tightly arrangedwith a plurality of neighboring OLED devices 406, 408 on the curvedsurface 404, housings of neighboring OLED devices do not substantiallyinterfere with each other. For example, when the slant angle α is about60°, two neighboring OLED devices 402, 406 may be arranged on a curvedsurface with such a curvature that the OLED devices 402, 406 form aninward angle of about 120°, while the neighboring sidewalls do not exertpressure on each other. In some embodiments, the slant angle α is in therange between about 30° and 90°. Accordingly, the individual devices402, 406, 408 can be substantially flat and rigid, while mosaics of suchdevices can cover curved surfaces of different curvatures.

The enclosure 414 formed between the housing 400 and the substrate maybe filled with an inert gas, such as argon, at a pressure equal to orhigher than an atmospheric pressure. This further helps prevent oxygenand water vapor from entering the enclosure 414. For example, thepressure may be between about 1.05 and 1.5 times the atmosphericpressure. The strength of the housing material and the active regionmaterial determines how high the pressure can be. In one embodiment, thepressure is about 1.1 times the atmospheric pressure.

In the top plan view, the housing 400 has a shape configured to improvethe fill factor, i.e., the ratio between the light emitting area to thetotal area, of the OLED device. The shape of the housing 400 in the topplan view may be a circle, an oval, or polygonal. The housing 400 may becoated with a color or labeled with a symbol indicative of a lightemission color of the active region, for example, red, green, blue, orwhite.

In some embodiments, the housing may comprise transparent plastic toallow light to pass therethrough. The housing may also be made of glass.The glass housing may be manufactured in a certain shape to improvelight out coupling.

Polygonal OLED Devices

In one exemplary embodiment, the housing may have a substantiallypolygonal shape, such as the hexagonal shape in the top plan view asshown in FIG. 5A. Thus, the OLED device 506 is configured to beneighboring six other polygonal OLED devices to form a tightly arrangedmosaic.

A plurality of OLED devices, which are pre-manufactured and can bealready packaged, are “plugged” or snuggly fit into a mount 502 andarranged in the pattern. In the embodiment shown in FIG. 5A, the modularOLED devices have hexagonal shapes to improve the density or fill factorof the lighting system. Those of ordinary skill in the art willrecognize that other shapes can also be used. For example, byappropriately selecting and patterning the modular OLED devices ofdifferent shapes (e.g., pentagons, hexagons, and triangles) and sizes, alighting system of complex 3-dimensional shapes, such as that of ageodesic dome, may be achieved.

Color Tuning

Advantageously as a result of the modular design discussed in thisapplication, the individual OLED devices may be selected from a kitcomprising devices with different color characteristics, sizes, andshapes.

At least one of the OLED devices is removably coupled to the mount 502,and the system is expandable to include more OLED devices. Accordingly,a mixed color of the emitted light from the lighting system isadjustable by selectively replacing at least a subset of OLED devices.For example, by replacing some of the blue OLED devices with red OLEDdevices, the color of the output light from the lighting system can beshifted toward a warmer color.

Alternatively, the individual OLED devices may be individually addressedand controlled using, for example, the controller 130 shown in FIGS. 1Aand 1B. The color of the emitted light from the lighting system istunable by selectively driving at least one of the plurality of OLEDdevices differently from other OLED devices. Driving the OLED devicesdifferently may be realized by driving the OLED devices to differentactivation levels. Such activation levels may include, for example,voltage levels, current levels, on/off states, and pulse widths.

For example, a drive voltage or a drive current of some of the pluralityof OLED devices may be selectively varied. By increasing the drivevoltage or the drive current of the blue OLEDs, the overall output colorof the lighting system is tuned toward a colder color temperature.

In another example, some of the OLED devices may be selectively turnedon or off to adjust the output color and luminosity.

In yet another example, the OLED devices are driven in a pulse widthmodulation (PWM) method, where the activation levels of the OLED devicesare determined by a drive pulse width. By selectively increasing thepulse width of, for example, some of the blue OLED devices, the outputcolor of the lighting system is tuned toward a colder color temperature.

OLED Device Wearing

In order to drive an OLED device to emit light, an electrical current ispassed through an active region or a light emitting layer of the device.One cause of “aging” or “wearing” of the device occurs when molecularbonds within the material making up the active region are broken orformed when photons, excitons, electrons and/or holes chemicallyinteract with the material. The presence of oxidants or reductants mayfacilitate such aging or wearing. OLED devices that emit differentcolors, for example, have different wearing and aging characteristics orprofiles. Blue OLEDs are generally known to age more quickly than redOLEDs, causing blue OLEDs to fail in a shorter period of time than redOLEDs under similar operating conditions.

Wear leveling refers to various approaches that can be undertaken toimprove the overall aging profile of a collection of OLED devices evenwhen the individual OLED devices within the collection have differentaging profiles. A wearing level of an OLED device may be determinedbased on, for example, an accumulative duration that the OLED device hasbeen previously activated. The prior activation history of the OLEDdevice may be recorded in a memory device. The history may include, forexample, drive voltage or current pulse width, frequency, amplitude, andaccumulative duration.

In addition, the wearing level of the OLED device may be characterizedby a measured current, a capacitance, a junction temperature, or aluminance of the OLED device. The current or the capacitance may bemeasured using the controller in conjunction with appropriate electricalcircuitry. The parameters such as the junction temperature may bemeasured locally using a temperature sensor adjacent to, or embedded in,the active region. The luminance may be measured by an optical detectorat a distance from the OLED device.

Expected Lifetime

When an OLED device has degraded to a predetermined level such that theOLED device emits light below a predetermined efficiency threshold, theOLED device is said to have reached its expected lifetime. Differenttypes of OLED devices have expected lifetime of different lengths. Forexample, blue OLEDs typically have shorter lifetime because of thehigher photon energy. The expected lifetime of conventional blue OLEDsis typically only about half that of red OLEDs or green OLEDs of thesame size when operated at conditions such that a mixed light output hasdesired characteristics, e.g., at certain color coordinates in colorspace.

When a certain number of OLED devices reach their lifetime, thecollection of OLED devices in the lighting system starts to have asignificantly degraded performance, and the lighting system is said tohave reached its own lifetime. In conventional lighting systems, thelifetimes of different types of OLED devices are not matched. Forexample, when blue OLED devices have reached their lifetime, OLEDdevices of other colors would be still usable. However, the colorcoordinates of the lighting system would have changed and reached itslifetime due to the degradation of the blue OLED devices.

As discussed below, lighting systems are provided with matchinglifetimes of different types of OLED devices. In a “low cost” approach,the degraded OLED devices may be simply replaced, taking advantage ofthe modular design of the OLED devices and their couplings to the mount.In another approach, pre-installed redundant OLED devices in thelighting system can be activated to replace or augment the degradeddevices. In yet another approach, the different types of OLED devicesare provided with different sizes and/or different drive currents,thereby substantially matching their lifetimes and effectively expandingthe lifetime of the lighting system.

Configurable Lighting System with Expanded Lifetime

In a lighting system, the plurality of OLED devices may include a firstnumber of a first type of OLED devices and a second number of a secondtype of OLED devices. The first type of OLED devices have a spectrum(e.g., color) different from a spectrum of the second type of OLEDdevices. An individual OLED device may have its lifetime correlated toits emission spectrum. Typically an OLED of shorter emission wavelengthhas a shorter lifetime, as discussed above with respect to blue OLEDdevices. This may result from the fact that the photons of shorterwavelength are more energetic so that they break the bonds in themolecules of the active region faster than do the photons of longerwavelengths.

Accordingly, the numbers of different types of OLED devices may beselected to be inversely proportional to their expected lifetime. In oneembodiment, the numbers of different types of OLED devices are selectedbased on their expected lifetime. For example, a two-to-one ratiobetween the number of blue OLEDs and the number of red OLEDs may bepredetermined. This ratio is based on the expected average lifetime ofthe blue OLED being only half that of the red OLED or green OLED.Accordingly, in the system shown in FIG. 5A, for every red OLED device504 or green OLED device 506, two blue OLED devices 508 are included.

In one embodiment, all the OLEDs may be simply driven by a commonvoltage and the blue OLEDs may be configured to have a higher resistanceand thus a lower current. During the wearing/aging of the lightingsystem, the color and other optical characteristics such as thebrightness are thus effectively controlled by the pre-selected numbersof different OLED devices. For example, the color coordinates of thelight output from the lighting system can be maintained by including alarger number of blue OLED devices, or blue OLED devices of larger sizesas compared with red or green OLED devices, while reducing the operatingcurrent densities of these blue OLED devices. The individual OLEDdevices of different types have substantially matched lifetimes in theresulting lighting system.

Wear Leveling

In the case of replacing some of the OLED devices for color tuning or toreplace the degraded devices, the newer OLED devices will have longerlifetime remaining as compared with older devices. That is, thedifferent devices have different wearing levels, and the older devicesor those devices that have been activated at higher levels have morewearing. Accordingly, a wear leveling method is provided to level outthe wearing of different devices thereby expanding the lifetime of thelighting system.

For example, the OLED devices may be configured to be selectivelyactivated to different levels. In one embodiment, at least some of theOLED devices are configured to be selectively turned on or off based ona lifetime of the at least some of the plurality of OLED devices. Inparticular, newer devices may be intentionally activated to higheractivation levels. Activating to higher activation levels may include,for example, turning on the device for a longer period of time or at ahigher frequency, or driving the device at a higher current density. Onthe other hand, those OLED devices of larger number, as discussed above,or of larger sizes, as discussed below, can be activated to loweractivation levels to match their lifetimes with other OLED devices whilemaintaining the color coordinates of the lighting system.

In one example, as illustrated in FIG. 5B, the blue OLED devicesreferenced as numbers 1 and 2 may be alternately driven by a voltagepulse over time. Thus, each of the blue OLED devices is activated onlyhalf of the time as compared with the red or green OLED devices whichwould be running continuously. Accordingly, the effective lifetime ofthe system is maintained despite the different expected lifetimes of thecomponents if operating continuously.

In some embodiments, the wearing of individual OLED devices is measuredby a sensor. The sensor may be, for example, a local sensor for sensinga junction temperature or a current across the junction. Alternatively,the sensor may be a remote sensor for sensing the light output. Thesensor provides means to detect those OLED devices having more wear, anda feedback mechanism to compensate for the uneven wearing/aging. Forexample, an OLED device with more wearing, as indicated by either ameasured parameter such as the current or the light output, or by thetotal time/cycles that the OLED device has been active, will becontrolled to be activated at lower levels as compared with those OLEDshaving less wearing.

In another embodiment, a feedback mechanism is included for driving theindividual OLED devices to compensate for aging rather than for wearleveling. For example, individual OLED devices may be monitored fortheir current, output, junction temperature, or other properties, whichare fed back into a control circuit to adjust the control voltage orcurrent. For example, when it is detected that an OLED device has alower drive current than normal, which likely results in lower lightoutput, the drive voltage on that OLED device may be increased. If oneof the OLED devices becomes defective and no longer produces light, abackup or redundant OLED device may be activated to replace the “dead”OLED device.

Reverse Bias Healing

As illustrated in FIG. 5C, the individual OLED devices may be driven bypulsed voltages, and the duty cycles include forward biases where thedevices are operated normally, and reverse biases where the devices maybe “healed” with defects being repaired by a reverse current.

Address Swapping

In one embodiment, a wear leveling mechanism is provided to selectivelyactivate, or to selectively control the activation levels of individualOLEDs, based on the wearing of the OLED devices. This may be achieved,for example, by swapping addresses of the OLED devices in controlcircuit memory. In one example, as illustrated in FIG. 5D, for the sametype of OLED devices B1, B2, and B3 with corresponding addresses of 001,002, and 003, a drive sequence may be 001/001/002/003 to realize adesired color and/or brightness characteristics. Accordingly, the OLEDdevice B1 wears more than B2 and B3. The controller determines that B1has been previously activated more often and thus is expected to have ashorter lifetime than that of B2 and B3. Accordingly, the addresses ofB1 and B2, or those of B1 and B3, may be swapped. That is, the addressesof B1, B2, B3 are now 002, 001, and 003, respectively. The same drivesequence 001/001/002/003 now drives B2 more often. After a time period,the addresses between B2 and B3 can be swapped so that the same drivesequence drives B3 more often, thereby leveling the wearing of the OLEDdevices B1, B2, and B3. Thus, the effective lifetime of the system isexpanded.

Emission Spectrum

The active region of the OLED device emits a relatively broad bandspectrum. For example, as illustrated in FIG. 6, individual OLED devicesmay be configured to emit in the blue (B), green (G), red (R), white(W), or the like, regime.

The FWHM of the individual spectrum may be larger than 50 nm. Preferablythe FWHM is larger than about 100 nm, and may be even larger than about200 nm in some cases. The broadband emission spectrum may have a colorselected from a white, a red, a green, a blue, a yellow, a orange, acyan, or a magenta color. By appropriately mixing different OLEDdevices, the output spectrum 600 can be visually substantially white.

The broadband emission spectrum 600 corresponds to a color renderingindex (CRI) higher than about 60, and preferably higher than about 80,or even higher than about 90. In one embodiment, the broadband emissionspectrum corresponds to a CRI of about 100.

Advantageously, the broadband spectra of individual OLED devices aremixed to form the output spectrum 600 which may be very close tonaturally white light to human eyes. This is in contrast to conventionallighting systems comprising inorganic LED devices, the spectra of whichhave a relatively narrow band, e.g., on the order of about 10 nm to 40nm. The resulting mixed light may not be naturally white even when theCRI is high.

The active region of the OLED device may be substantially transparent.The anode may comprise a transparent conductor, for example, indium tinoxide (ITO). The cathode may comprise one of a metal or a metal alloy,such as aluminum-copper, or an organo-metallic material. In someembodiments, the cathode may also comprise a transparent conductor. Whenmostly transparent layers are used, a plurality of OLED devices may bevertically stacked without blocking light emission from individualdevices. In addition, an OLED device may include a plurality ofvertically-stacked transparent OLED chips, which are not stand-alonedevices as they may not have their own encapsulations, but may havetheir own substrates and electrodes and can be individually controlled.

OLED Kit

The OLED structure illustrated in FIG. 1, as well as other basic OLEDstructures, can be applied to a modular design of OLED devices forlighting. In particular, a plurality of pre-manufactured modular OLEDdevices may be provided, and the individual modular OLED devices can beselected and “plugged” into a mount, thereby forming a configurablelighting system. The system can have desired optical properties, such asthe color, by selecting an appropriate set of OLED devices to couple tothe mount.

The pre-manufactured OLED devices such as that illustrated in FIG. 1 canbe provided in a kit. The kit can include at least two types ofpre-manufactured, modular, replaceable, OLED devices of differentcolors, each OLED device comprising a substrate, an anode, a cathode,and an active region comprising an organic material.

In addition to different colors, OLED devices with different sizes anddifferent shapes may be provided. The active region may have a directemission area that is very large, e.g., on the order of one meter orlarger. The size may be limited by manufacturing processes. Preferably,the active region has a lateral dimension larger than about 0.5centimeter. The active region preferably has an area larger than 25 mm².Various OLED shapes may include circular or polygonal shapes.

The OLED devices may already have couplers attached thereto, and thusare “plug and play” devices.

Although in FIG. 1 it is shown that the couplers are shown pre-linked tothe OLED devices or to the mount, as illustrated in FIGS. 9A-9D, thecouplers can be provided as standalone components of the kit. At leastone of the plurality of couplers has at least one conductive surfacearea and at least one insulating surface area at predetermined locationsfor electrically coupling one of the OLED devices with another OLEDdevice, or with the mount.

The kit may further comprise a homogenizer to reduce the pixilatedappearance of an OLED array.

The kit may further comprise a power supply, a mount for receiving atleast some of the plurality of OLED devices, and a set of instructionsfor assembling a subset of the components selected from the kit. Also,the kit can comprise a controller configured to drive the OLED devices,including a controller configured to selectively drive at least some ofthe plurality of OLED devices at different activation levels.

OLED Devices Having Different Sizes

The processing technologies, such as ink-jet printing, screen printing,Micro Gravure™, etc., allow the solution processable components of anOLED to be fabricated on well-defined and optionally patterned areas.Spin coating, slot-die coating, gravure coating, doctor blading, and thelike allow for application of the solution processable components of anOLED to be applied to large area substrates. In addition, the OLEDdevices can be fabricated with active regions of different sizes. Thus,instead of different numbers of different types of OLED devices ofsimilar sizes, a lighting system with OLED devices of different sizescan be assembled.

For example, a plurality of OLED devices can be provided including afirst type of OLED devices each having a first size, and a second typeof OLED devices each having a second size. The lifetime of an OLEDdevice depends not only on the emission spectrum as discussed above, butalso on the current density flowing through the active region of theOLED device. That is, for a lower current density, there are fewerphotoemissions per unit area in the active region, and the lifetime ofthe OLED device may be longer than a similar device operated at highercurrent density.

Accordingly, a lighting system can be configured to have different typesof OLED devices with different sizes, thereby increasing the effectivelifetime of the lighting system. If the first type of OLED devices havea first expected lifetime, and the second type of OLED devices have asecond expected lifetime, the lighting system can be constructed withthe first type of OLED devices each having a first size, and with thesecond type of OLED devices each having a second size. A ratio of thefirst size to the second size can be configured approximatelyproportional to a ratio of the second expected lifetime to the firstexpected lifetime. The first type of OLED devices can then be driven ata first current density, and the second type of OLED devices can bedriven at a second current density. A ratio of the first current densityto the second current density can be configured approximatelyproportional to a ratio of the second size to the first size. In oneembodiment, the ratio of the first current density to the second currentdensity approximately equals a ratio of the second size to the firstsize.

In one example system 700 shown in FIG. 7, the plurality of OLED devicescoupled to the mount 702 include blue OLED devices 704, red OLED devices706, and green OLED devices 708. Each of the blue OLED devices 704 hasan active region of a size about twice the size of the active region ofthe red OLED device 706 or the green OLED device 708. In one example,the active region of the blue OLED device 704 has a dimension of about 1cm×2 cm, while the red OLED device 706 and the green OLED device eachhas an active region of about 1 cm×1 cm. The blue OLED devices 704 canthus be driven at about the half current density of that of the red OLEDdevice 706, thereby effectively increasing the lifetime of the blue OLEDdevices. As such, the expected lifetime of the system 700 is improved bychoosing the sizes, and/or current densities or other parameters, of theindividual devices to have substantially matching lifetimes.

OLED Device Assembled from the Kit

A customer, such as a consumer electronics manufacturer or a consumer,may select a subset of OLED devices from the kit, and assemble alighting or signage apparatus with appropriate selection of OLED deviceshaving different colors and brightness.

For example, in FIG. 8, a stacked OLED configuration is shown, where aplurality of OLED devices 802, 804, 806 are stacked vertically.Electrodes 808 which connect to the OLED device anode and cathode may bearranged on the side, and the individual OLED devices may havetransparent substrates such as glass. The stacked OLED structureincreases the total light output per unit area, while the individualOLED devices may be driven at a relatively low current, therebyincreasing their lifetime.

Alternative to using semi-transparent substrates, anodes, and cathodes,light may be coupled out from the edges of the stack, for example, usinggratings and waveguides.

Vertical Coupling of Stacked OLED Devices

A method of coupling an OLED device vertically with another OLED device,or with a mount to form a lighting system, is illustrated in FIG. 9A.The OLED device 902 and the mount 904 can have pre-fabricated openings906, in which elongated conductors 908 may be fit in. The openings 906may be etched or machined, depending on the substrate material of theOLED device 902 or the mount 904. Alternatively, openings 906 can bepierced by couplers 908 during the assembling process.

The elongated conductors 908 have patterned outer surface areas withinsulating regions 910 and conductive regions at desired locations suchthat, when fitted into the openings 906, proper electrical paths andinsulations among the vertical layers may be formed. The elongatedconductors 908 may be snuggly fit into the openings 906, or by threadedengaging. The elongated conductor 908 may be flexible to accommodate aflexible system. The elongated conductor is configured to bothmechanically and electrically couple one of the OLED devices 902 withanother one of the OLED devices or with the mount 904.

In the mount 904 shown in FIG. 9A, two conductive layers 912 and 914 areincluded. When the elongated conductor 908 is coupled to the mount 904and the OLED device 902, the insulating region 910 comes into contactwith the second conductive layer 914. Accordingly, an electricalconnection is established between the first conductive layer 912 and theOLED device 902 through the elongated conductor 908. By prearranging thelocations of the insulating regions and the conductive layers, complexelectrical connections may be established.

In another example shown in FIG. 9B, two elongated conductors areincluded each having insulating regions located at different locations.These locations may correspond to the depth of the two conductivelayers. As shown, once both elongated conductors are coupled to the OLEDdevice and the mount, two electrodes of the OLED device may be coupledto the first and second conductive layers, respectively.

Further, in an embodiment shown in FIG. 9C, an integrated connector 930may be used. The integrated connector 930 has a substantially “U” shapewith two “arms” and resembles a staple. Insulating regions are disposedat different locations of the integrated connector 930. Those ofordinary skill in the art will recognize that connectors of other shapeswith more “arms” are possible.

As shown in FIG. 9D, an example OLED device 940 has one or more contactpads 942. The OLED device 940 can be coupled to a mount, or to anotherOLED device 944, using elongated conductors 946 that may be “stapled”through the contact pads 942. In one embodiment, a nail gun (not shown)can be used to drive he elongated conductors 946 to pierce through thecontact pads 942 or the OLED device 940. As shown, the elongatedconductors 946 can be electrically coupled to both OLED devices 940, 944through their respective contact pads and the electrical paths 948. Theelectrical paths 948 can be printed on the OLED devices, or fabricatedtogether with the electrodes and the active layers.

The modular OLED devices, which can be pre-manufactured and may bealready packaged, may be “plugged in” to a mount and arranged in apattern. Advantageously as a result of the modular design, theindividual OLED devices may be selected from a kit comprising deviceswith different color characteristics, sizes, and shapes.

In one embodiment, the modular OLED devices are selected and disposed onthe mount in a ratio based on their expected lifetime. For example, atwo-to-one ratio between the number of blue OLEDs and the number of redOLEDs may be predetermined based on that the lifetime of the blue OLEDis about half that of the red OLED.

In one example, more blue OLED devices, which typically have shorterlifetimes, are included in the lighting system, as compared with red orgreen OLED devices. For example, for every red or green OLED, two (2)blue OLED devices may be included. The two blue OLED devices may bealternately activated as controlled by a controller.

In a “low cost” approach, all the OLED devices may be simply driven by asame voltage and the blue OLEDs may be configured to have higherresistance and thus lower current. This also would improve the lifetimeof the blue OLED devices, while the increased number of these blue OLEDdevices compensates for the lower activation levels to realize thedesired luminance and color characteristics.

During the wearing/aging of the lighting system, the color and otheroptical characteristics are thus effectively controlled by the selectionof the OLED devices.

As discussed above with respect to planar lighting systems, thevertically-stacked OLED devices can also be individually controlled by acontroller to achieve color tuning, aging compensation, and wearleveling.

Further Embodiments

Priority provisional application Ser. No. 61/102,326 filed Oct. 2, 2008is incorporated by reference including the following embodiments:

In one embodiment, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The activation levels are characterizedby at least one of a drive voltage level, a drive current level, a pulsewidth, a pulse frequency, an on state, or an off state.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The plurality of OLED devices include afirst number of a first type of OLED devices and a second number ofsecond type of OLED devices. The first type of OLED devices have colorcharacteristics different from the second type of OLED devices.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The plurality of OLED devices include afirst number of a first type of OLED devices and a second number ofsecond type of OLED devices, and the first type of OLED devices havecolor characteristics different from the second type of OLED devices.Furthermore, the first type of OLED devices have an expected lifetimeshorter than an expected lifetime of the second type of OLED devices,and the first number is larger than the second number.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The plurality of OLED devices include afirst number of a first type of OLED devices and a second number ofsecond type of OLED devices, and the first type of OLED devices havecolor characteristics different from the second type of OLED devices.Furthermore, the first type of OLED devices have an expected lifetimeshorter than an expected lifetime of the second type of OLED devices,and the first number is correspondingly larger than the second number.The controller is configured to alternately activate at least some ofthe first type of OLED devices thereby increasing a lifetime of thelighting system.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The plurality of OLED devices include afirst number of blue OLED devices, a second number of red OLED devices,and a third number of green OLED devices. The first number is abouttwice the second number. The controller is configured to alternatelyactivating neighboring blue OLED devices thereby increasing a lifetimeof the lighting system.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. At least some of the plurality of OLEDdevices are configured to be selectively driven at different activationlevels to improve a lifetime of the lighting system based on differentwearing levels of the plurality of OLED devices.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. At least some of the plurality of OLEDdevices are configured to be selectively driven at different activationlevels to improve a lifetime of the lighting system based on differentwearing levels of the plurality of OLED devices. A wearing level of anOLED device is determined based on one or more of an accumulativeduration that the OLED device has been previously activated, a measuredcurrent, a capacitance, a junction temperature, or a luminance of theOLED device.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The controller is configured toselectively drive at least some of the plurality of OLED devices todifferent activation levels to compensate for degradation of some of theplurality of OLED devices thereby maintaining the desired output colorcharacteristics.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The lighting system further comprises asensor for sensing a degradation of one or more of the plurality of OLEDdevices. The controller is configured to drive the one or more of theplurality of OLED devices to different activation levels to compensatefor the sensed degradation.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The lighting system further comprises asensor for sensing a degradation of one or more of the plurality of OLEDdevices. The controller is configured to increase a drive voltage or adrive current of the one or more of the plurality of OLED devices tocompensate for the sensed degradation.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The lighting system further comprises asensor for sensing a degradation of one or more of the plurality of OLEDdevices. At least some of the plurality of OLED devices are redundantOLED devices, and the controller is configured to turn on one or more ofthe redundant OLED devices to compensate for the sensed degradation.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The lighting system further comprises asensor for sensing a degradation of one or more of the plurality of OLEDdevices. The sensor is configured to sense one of a temperature, acurrent, a capacitance, or a luminance of the one or more of theplurality of OLED devices.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. The controller is further configured totune a color of light emitted from the lighting system by selectivelydriving at least some of the plurality of OLED devices at activationlevels different from some other of the plurality of OLED devices.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. At least some of the plurality of OLEDdevices are vertically stacked.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. At least some of the plurality of OLEDdevices are vertically stacked, and at least one of the verticallystacked OLED devices is substantially transparent in the verticaldirection.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. At least some of the plurality of OLEDdevices are vertically stacked, and at least some of the verticallystacked OLED devices have a transparent glass substrate.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. At least some of the plurality of OLEDdevices are vertically stacked, and at least one of the verticallystacked OLED devices is configured as an edge-emitting OLED device.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. At least some of the plurality of OLEDdevices are vertically stacked. The lighting system further comprises anedge emitting coupler for improving light output from an edge of atleast one of the vertically stacked OLED devices. The edge emittingcoupler comprises at least one of a grating or a waveguide.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. At least some of the plurality of OLEDdevices are vertically stacked, and at least two of the OLED devices areconfigured to emit light of different colors.

In another embodiment, a lighting system is provided. The lightingsystem has a plurality of OLED devices and a controller configured toindependently control activation levels of at least some of theplurality of OLED devices based on their expected lifetime to increase alifetime of the lighting system. At least some of the plurality of OLEDdevices are vertically stacked, and at least some of the plurality ofOLED devices are substantially transparent.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices, wherein each of the plurality of OLEDdevices has an active region. At least some of the OLED devices haveactive regions of different sizes, and the different sizes are selectedsuch that light emitted from the lighting system has desired colorcharacteristics and that the OLED devices having active regions ofdifferent sizes have substantially matching lifetimes.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices, wherein each of the plurality of OLEDdevices has an active region. At least some of the OLED devices haveactive regions of different sizes, and the different sizes are selectedsuch that light emitted from the lighting system has desired colorcharacteristics and that the OLED devices having active regions ofdifferent sizes have substantially matching lifetimes. The plurality ofOLED devices include a first type of OLED devices each having an activeregion of a first size and a first expected lifetime, and a second typeof OLED devices each having an active region of a second size and asecond expected lifetime. A ratio of the first size to the second sizeis approximately proportional to a ratio of the second expected lifetimeto the first expected lifetime, wherein the first type of OLED devicesare driven at a first current density, and the second type of OLEDdevices are driven at a second current density. A ratio of the firstcurrent density to the second current density is approximatelyproportional to a ratio of the second size to the first size therebysubstantially matching actual lifetimes of the first type of OLEDdevices and the second type of OLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices, wherein each of the plurality of OLEDdevices has an active region. At least some of the OLED devices haveactive regions of different sizes, and the different sizes are selectedsuch that light emitted from the lighting system has desired colorcharacteristics and that the OLED devices having active regions ofdifferent sizes have substantially matching lifetimes.

The plurality of OLED devices include a first type of OLED devices eachhaving an active region of a first size and a first expected lifetime,and a second type of OLED devices each having an active region of asecond size and a second expected lifetime. A ratio of the first size tothe second size is approximately equal to a ratio of the second expectedlifetime to the first expected lifetime, wherein the first type of OLEDdevices are driven at a first current density, and the second type ofOLED devices are driven at a second current density. A ratio of thefirst current density to the second current density is approximatelyequal to a ratio of the second size to the first size therebysubstantially matching actual lifetimes of the first type of OLEDdevices and the second type of OLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices, wherein each of the plurality of OLEDdevices has an active region. At least some of the OLED devices haveactive regions of different sizes, and the different sizes are selectedsuch that light emitted from the lighting system has desired colorcharacteristics and that the OLED devices having active regions ofdifferent sizes have substantially matching lifetimes. The plurality ofOLED devices include a first plurality of active regions configured toemit substantially red light, a second plurality of active regionsconfigured to emit substantially green light, and a third plurality ofactive regions configured to emit substantially blue light. At leastsome of the third plurality of active regions have increased sizes andcorrespondingly reduced current densities as compared with the firstplurality and the second plurality of active regions to increase anactual lifetime of the third plurality of active regions.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices, wherein each of the plurality of OLEDdevices has an active region. At least some of the OLED devices haveactive regions of different sizes, and the different sizes are selectedsuch that light emitted from the lighting system has desired colorcharacteristics and that the OLED devices having active regions ofdifferent sizes have substantially matching lifetimes. The plurality ofOLED devices include a first plurality of red OLED devices, a secondplurality of green OLED devices, and a third plurality of blue OLEDdevices. Each of the third plurality of blue OLED devices has an activeregion about twice the size of each of the red OLED devices, and each ofthe third plurality of blue OLED devices is driven at a reduced currentdensity to increase an actual lifetime of the blue OLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices, wherein each of the plurality of OLEDdevices has an active region. At least some of the OLED devices haveactive regions of different sizes, and the different sizes are selectedsuch that light emitted from the lighting system has desired colorcharacteristics and that the OLED devices having active regions ofdifferent sizes have substantially matching lifetimes. At least one ofthe plurality of OLED device has at least one coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices, wherein each of the plurality of OLEDdevices has an active region. At least some of the OLED devices haveactive regions of different sizes, and the different sizes are selectedsuch that light emitted from the lighting system has desired colorcharacteristics and that the OLED devices having active regions ofdifferent sizes have substantially matching lifetimes. At least some ofthe plurality of OLED devices are vertically stacked, and at least twoof the OLED devices are configured to emit light of different colors.

In another embodiment, a method is provided. The method comprisesselectively controlling activation levels of at least some of aplurality of OLED devices based on their expected lifetime to improve alifetime of the lighting system.

In another embodiment, a method is provided. The method comprisesselectively controlling activation levels of at least some of aplurality of OLED devices based on their expected lifetime to improve alifetime of the lighting system.

The method further comprises determining wearing levels of the at leastsome of the plurality of OLED devices. In this embodiment theselectively controlling activation levels of at least some of theplurality of OLED devices comprises selectively controlling the at leastsome of the plurality of OLED devices based on the determined wearinglevels the OLED devices, wherein a wearing level of an OLED device isdetermined based on one or more of an accumulative duration that theOLED device has been previously activated, a measured current, acapacitance, a junction temperature, or a luminance of the OLED device.

In another embodiment, a method is provided. The method comprisesselectively controlling activation levels of at least some of aplurality of OLED devices based on their expected lifetime to improve alifetime of the lighting system. The method further comprises assigningaddresses to the at least some of the plurality of OLED devices andswapping addresses between at least a first OLED device and a secondOLED device among the at least some of the plurality of OLED devices.The first and second OLED devices have different wearing levels. Awearing level of an OLED device is determined based on one or more of anaccumulative duration that the OLED device has been previouslyactivated, a measured current, a capacitance, a junction temperature, ora luminance of the OLED device.

In another embodiment, a method is provided. The method comprisesselectively controlling activation levels of at least some of aplurality of OLED devices based on their expected lifetime to improve alifetime of the lighting system.

The plurality of OLED devices include a first type of OLED devices. Themethod further comprises alternately activating some of the first typeof OLED devices thereby improving a lifetime of the lighting system.

In another embodiment, a method is provided. The method comprisesselectively controlling activation levels of at least some of aplurality of OLED devices based on their expected lifetime to improve alifetime of the lighting system.

The plurality of OLED devices include a first number of blue OLEDdevices, a second number of red OLED devices, and a third number ofgreen OLED devices. The first number is about twice the second number.The method further comprises alternately activating neighboring blueOLED devices thereby increasing a lifetime of the lighting system.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the plurality of OLED devices to different activationlevels such that an output light from the lighting system has a desiredcolor characteristics. At least one of the plurality of OLED devices hasat least one coupler configured to electrically couple the OLED deviceto a power supply and an encapsulation that isolates the OLED devicefrom an ambient environment.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the plurality of OLED devices to different activationlevels such that an output light from the lighting system has a desiredcolor characteristics. At least one of the plurality of OLED devices hasat least one coupler configured to electrically couple the OLED deviceto a power supply and an encapsulation that isolates the OLED devicefrom an ambient environment. The activation levels are characterized byat least one of a drive voltage level, a drive current level, a drivepulse width, a drive pulse frequency, an on state, or an off state.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the plurality of OLED devices to different activationlevels such that an output light from the lighting system has a desiredcolor characteristics. At least one of the plurality of OLED devices hasat least one coupler configured to electrically couple the OLED deviceto a power supply and an encapsulation that isolates the OLED devicefrom an ambient environment. A color of light emitted from the lightingsystem is tunable by selectively varying activation levels of at leastsome of the plurality of OLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the plurality of OLED devices to different activationlevels such that an output light from the lighting system has a desiredcolor characteristics. At least one of the plurality of OLED devices hasat least one coupler configured to electrically couple the OLED deviceto a power supply and an encapsulation that isolates the OLED devicefrom an ambient environment. A color of light emitted from the lightingsystem is tunable by selectively varying at least one of a drive voltageor a drive current of at least some of the plurality of OLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the plurality of OLED devices to different activationlevels such that an output light from the lighting system has a desiredcolor characteristics. At least one of the plurality of OLED devices hasat least one coupler configured to electrically couple the OLED deviceto a power supply and an encapsulation that isolates the OLED devicefrom an ambient environment. The controller is configured to selectivelydrive at least some of the plurality of OLED devices to differentactivation levels to compensate for degradation of some of the pluralityof OLED devices thereby maintaining the desired output colorcharacteristics.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the plurality of OLED devices to different activationlevels such that an output light from the lighting system has a desiredcolor characteristics. At least one of the plurality of OLED devices hasat least one coupler configured to electrically couple the OLED deviceto a power supply and an encapsulation that isolates the OLED devicefrom an ambient environment. The lighting system further comprises asensor for sensing a degradation of one or more of the plurality of OLEDdevices, wherein the controller is configured to drive one or more ofthe plurality of OLED devices to different activation levels tocompensate for the sensed degradation.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the plurality of OLED devices to different activationlevels such that an output light from the lighting system has a desiredcolor characteristics. At least one of the plurality of OLED devices hasat least one coupler configured to electrically couple the OLED deviceto a power supply and an encapsulation that isolates the OLED devicefrom an ambient environment. The lighting system further comprises asensor for sensing a degradation of one or more of the OLED devices. Thecontroller is configured to increase a drive voltage or a drive currentof one or more of the OLED devices to compensate for the senseddegradation.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. The lighting system further comprises a sensor forsensing a degradation of one or more of the OLED devices. At least someof the OLED devices are redundant OLED devices, and the controller isconfigured to turn on one or more of the redundant OLED devices tocompensate for the sensed degradation.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. The lighting system further comprises a sensor forsensing a degradation of one or more of the OLED devices. The sensor isconfigured to sense one of a temperature, a current, a capacitance, or aluminance of one or more OLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. The controller is configured to drive at least someof the OLED devices to different activation levels to expand a lifetimeof the lighting system.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. The controller is configured to selectively turn onor off at least some of the OLED devices based on an expected lifetimeof the OLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. The controller is configured to selectively driveat least some of the OLED devices to different activation levels toexpand a lifetime of the lighting system. The different activationlevels include different drive pulse widths.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. The plurality of OLED devices include a firstnumber of a first type of OLED devices and a second number of a secondtype of OLED devices, and the first type of OLED devices have a lightemission spectrum different from a light emission spectrum of the secondtype of OLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. The plurality of OLED devices include a firstnumber of a first type of OLED devices and a second number of a secondtype of OLED devices, and the first type of OLED devices have a lightemission spectrum different from a light emission spectrum of the secondtype of OLED devices. Furthermore, the first type of OLED devices havean expected lifetime shorter than the second type of OLED devices, andthe first number is correspondingly larger than the second number.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. The plurality of OLED devices include a firstnumber of a first type of OLED devices and a second number of a secondtype of OLED devices, and the first type of OLED devices have a spectrumdifferent from a spectrum of the second type of OLED devices.Furthermore, the first type of OLED devices have a lifetime shorter thanthe second type of OLED devices, and the first number is correspondinglylarger than the second number. The controller is configured toselectively drive the first type of OLED devices to different activationlevels such that not all of the first type of OLED devices are turned onat the same time thereby increasing the lifetime of the first type ofOLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. At least some of the plurality of OLED devices arevertically stacked.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. At least some of the plurality of OLED devices arevertically stacked, and at least some of the vertically stacked OLEDdevices have a transparent substrate.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. At least some of the plurality of OLED devices arevertically stacked, and at least some of the vertically stacked OLEDdevices have a transparent glass substrate.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. At least some of the plurality of OLED devices arevertically stacked, and are configured as edge-emitting OLED devices.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. At least some of the plurality of OLED devices arevertically stacked. The lighting system further comprises an edgeemitting coupler for improving light output from an edge of thevertically stacked OLED devices. The edge emitting coupler comprises atleast one of a grating or a waveguide.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. At least some of the plurality of OLED devices arevertically stacked, and at least two of the OLED devices are configuredto emit light of different colors.

In another aspect, a lighting system is provided. The lighting systemhas a plurality of OLED devices and a controller configured toselectively drive the OLED devices to different activation levels suchthat an output light from the lighting system has a desired colorcharacteristics. At least one of the OLED devices has at least onecoupler configured to electrically couple the OLED device to a powersupply and an encapsulation that isolates the OLED device from anambient environment. At least some of the plurality of OLED devices arevertically stacked, and at least one of the plurality of OLED devices issubstantially transparent.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.At least some of the OLED devices emit light of different spectra, andthe spectra have colors selected from red, green, blue, cyan, magenta,or white.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.The coupler is removable from the OLED device.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.In this embodiment, a color of light emitted from the lighting system ischangeable by selectively replacing at least a subset of OLED devices.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.The plurality of OLED devices include a first number of a first type ofOLED devices and a second number of a second type of OLED devices, andthe first type of OLED devices have a spectrum different from a spectrumof the second type of OLED devices.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.The plurality of OLED devices include a first number of a first type ofOLED devices and a second number of a second type of OLED devices, andthe first type of OLED devices have a spectrum different from a spectrumof the second type of OLED devices. Furthermore, the first number islarger than the second number, and at least some of the first type ofOLED devices are driven at a reduced activation level to increase anaverage lifetime of the first type of OLED devices to be comparable witha lifetime of the second type of OLED devices.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.The plurality of OLED devices include a first number of a first type ofOLED devices and a second number of a second type of OLED devices, andthe first type of OLED devices have a spectrum different from a spectrumof the second type of OLED devices. Furthermore, the first type of OLEDdevices have an expected lifetime shorter than an expected lifetime ofthe second type of OLED devices, and the first number is correspondinglylarger than the second number. The controller is configured toselectively activate the first type of OLED devices such that not all ofthe first type of OLED devices are activated at the same time therebysubstantially matching lifetimes of the first type of OLED devices andthe second type of OLED devices while maintaining color coordinates.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.At least some of the plurality of OLED devices are vertically stacked.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.At least some of the plurality of OLED devices are vertically stacked,and at least one of the plurality of OLED devices is substantiallytransparent.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.At least some of the plurality of OLED devices are vertically stacked,and at least one of the plurality of OLED devices is configured as anedge-emitting OLED device.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.At least some of the plurality of OLED devices are vertically stacked.The system further comprises an edge emitting coupler for improvinglight output from an edge of the vertically stacked OLED devices. Theedge emitting coupler comprises at least one of a grating or awaveguide.

In another embodiment, a lighting system is provided. The lightingsystem has a mount and a plurality of OLED devices removably coupled tothe mount. The plurality of OLED devices are selected such that thelighting system emits light with desired color characteristics. At leastone of the plurality of OLED devices has a coupler configured toelectrically couple the OLED device to a power supply and anencapsulation that isolates the OLED device from an ambient environment.At least some of the plurality of OLED devices are vertically stacked,and at least two of the OLED devices are configured to emit light ofdifferent colors.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. Selecting the subset of OLED devicescomprises selecting a first number of a first type of OLED devices and asecond number of a second type of OLED devices. In this aspect, thefirst type of OLED devices have a first spectrum different from a secondspectrum of the second type of OLED devices.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. Selecting the subset of OLED devicescomprises selecting a first number of a first type of OLED devices and asecond number of a second type of OLED devices. In this aspect the firsttype of OLED devices have a first spectrum different from a secondspectrum of the second type of OLED devices. Thee first type of OLEDdevices have an expected lifetime substantially shorter than an expectedlifetime the second type of OLED devices, and selecting the subset ofOLED devices comprises selecting the first number substantially largerthan the second number.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. Selecting the subset of OLED devicescomprises selecting a first number of a first type of OLED devices and asecond number of a second type of OLED devices. In this aspect, thefirst type of OLED devices have a first spectrum different from a secondspectrum of the second type of OLED devices, and the first type of OLEDdevices have an expected lifetime substantially shorter than an expectedlifetime of the second type of OLED devices. Selecting the subset ofOLED devices comprises selecting the first number substantially largerthan the second number. The method further comprises selectivelyactivating the first type of OLED devices such that not all of the firsttype of OLED devices are activated at the same time thereby increasingthe lifetime of the first type of OLED devices.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. Selecting the subset of OLED devicescomprises selecting a first number of a first type of OLED devices and asecond number of a second type of OLED devices. In this aspect, thefirst type of OLED devices have a first spectrum different from a secondspectrum of the second type of OLED devices, and the first type of OLEDdevices have an expected lifetime substantially shorter than an expectedlifetime of the second type of OLED devices. Selecting the subset ofOLED devices comprises selecting the first number substantially largerthan the second number. The method further comprises selectivelyactivating the first type of OLED devices such that not all of the firsttype of OLED devices are activated at the same time thereby increasingan average lifetime of the first type of OLED devices. Selectivelyactivating the first type of OLED devices comprises electrically drivingthe first type of OLED devices with voltage or current pulses shorterthan those of the second type of OLED devices.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. Selecting the subset of OLED devicescomprises selecting a first number of a first type of OLED devices and asecond number of a second type of OLED devices. In this aspect, thefirst type of OLED devices have a first spectrum different from a secondspectrum of the second type of OLED devices, and the first type of OLEDdevices have an expected lifetime substantially shorter than an expectedlifetime of the second type of OLED devices. Selecting the subset ofOLED devices comprises selecting the first number substantially largerthan the second number.

The method further comprises selectively activating the first type ofOLED devices such that not all of the first type of OLED devices areactivated at the same time thereby increasing an average lifetime of thefirst type of OLED devices. Selectively activating the first type ofOLED devices comprises electrically driving the first type of OLEDdevices with current pulses, wherein electrically driving the first typeof OLED devices with current pulses comprises reversely biasing thefirst type of OLED devices during part of the current pulses to heal thefirst type of OLED devices.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. The method further comprisesselectively driving at least some of the plurality of OLED devices todifferent activation levels to compensate for degradation of some of theplurality of OLED devices thereby maintaining the desired output colorcharacteristics.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. The method further comprises sensinga degradation of one or more OLED devices and driving one or more ofOLED devices at different activation levels to compensate for the senseddegradation.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. The method further comprises sensinga degradation of one or more OLED devices and increasing a drive voltageor a drive current of one or more OLED devices to compensate for thesensed degradation.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. The method further comprises sensinga degradation of one or more of the plurality of OLED devices, whereinat least some of the plurality of OLED devices are redundant OLEDdevices, and turning on one or more of the redundant OLED devices tocompensate for the sensed degradation.

In another aspect, a method is provided. The method comprises selecting,from a kit of pre-manufactured modular OLED devices, a subset of OLEDdevices and coupling the selected subset of OLED devices to a mount. Thesubset of OLED devices is selected to have a mixed output light spectrumwith desired color characteristics. The method further comprises sensinga degradation of one or more OLED devices by measuring one of atemperature, a current, a capacitance, or a luminance of the OLEDdevices.

In another embodiment, a lighting system is provided. The lightingsystem has a mount, a plurality of couplers, and a plurality of OLEDdevices removably coupled to the mount through the plurality ofcouplers. The plurality of OLED devices are selected such that thelighting system emits light with a desired color characteristics. Atleast one of the OLED devices comprises an encapsulation that isolatesthe OLED device from an ambient environment.

In another embodiment, a lighting system is provided. The lightingsystem has a mount, a plurality of couplers, and a plurality of OLEDdevices removably coupled to the mount through the plurality ofcouplers. The plurality of OLED devices are selected such that thelighting system emits light with a desired color characteristics. Atleast one of the OLED devices comprises an encapsulation that isolatesthe OLED device from an ambient environment. In this embodiment, atleast one of the plurality of couplers is fixedly coupled with one ofthe plurality of OLED devices.

In another embodiment, a lighting system is provided. The lightingsystem has a mount, a plurality of couplers, and a plurality of OLEDdevices removably coupled to the mount through the plurality ofcouplers. The plurality of OLED devices are selected such that thelighting system emits light with a desired color characteristics. Atleast one of the OLED devices comprises an encapsulation that isolatesthe OLED device from an ambient environment. In this embodiment, atleast one of the plurality of couplers is fixedly coupled with themount.

In another embodiment, a lighting system is provided. The lightingsystem has a mount, a plurality of couplers, and a plurality of OLEDdevices removably coupled to the mount through the plurality ofcouplers. The plurality of OLED devices are selected such that thelighting system emits light with a desired color characteristics. Atleast one of the OLED devices comprises an encapsulation that isolatesthe OLED device from an ambient environment. In this embodiment, thecouplers are configured to electrically couple the OLED devices to apower supply.

In another aspect, a kit is provided. The kit has a plurality of OLEDdevices and a plurality of couplers.

In another aspect, a kit is provided. The kit has a plurality of OLEDdevices and a plurality of couplers. At least one of the plurality ofcouplers is pre-linked to one of the plurality of OLED devices.

In another aspect, a kit is provided. The kit has a plurality of OLEDdevices and a plurality of couplers. The kit further comprises a mountfor receiving at least some of the OLED devices. At least one of thecouplers is pre-linked to the mount.

In another aspect, a kit is provided. The kit has a plurality of OLEDdevices and a plurality of couplers. The kit further comprises a powersupply. The couplers are configured to electrically couple the OLEDdevices to a power supply.

In another aspect, a kit is provided. The kit has a plurality of OLEDdevices and a plurality of couplers. The kit further comprises a set ofinstructions for assembling the OLED devices and couplers.

The embodiments shown in FIGS. 1-9 are exemplary. Other embodiments canbe prepared within the spirit and scope of the claims by one skilled inthe art.

1. A lighting system comprising: a plurality of organic light emittingdiode (OLED) devices; a controller configured to selectively drive atleast some of the plurality of OLED devices at different activationlevels; and a sensor configured to sense a degradation at least one ofthe plurality of OLED devices, wherein at least one of the plurality ofOLED devices comprises: at least one coupler configured to electricallycouple the OLED device to a power supply; and an encapsulation thatisolates the OLED device from an ambient environment, wherein at leastsome of the plurality of OLED devices are redundant OLED devices, andwherein the controller is configured to turn on one or more of theredundant OLED devices to compensate for the sensed degradation.
 2. Thelighting system of claim 1, wherein the controller is configured toselectively drive at least some of the plurality of OLED devices atdifferent activation levels by controlling at least one of a drivevoltage level, a drive current level, a pulse width, a pulse frequency,an on state, or an off state.
 3. The lighting system of claim 1, whereinthe controller is configured to selectively drive at least some of theplurality of OLED devices at different activation levels to improve alifetime of the lighting system.
 4. The lighting system of claim 1,wherein the controller is configured to selectively drive at least someof the plurality of OLED devices at different activation levels toimprove a lifetime of the lighting system based on different wearinglevels of the plurality of OLED devices.
 5. The lighting system of claim1, wherein the controller is configured to selectively drive at leastsome of the plurality of OLED devices at different activation levels toimprove a lifetime of the lighting system based on different wearinglevels of the plurality of OLED devices, and wherein a wearing level ofan OLED device is determined based on one or more of an accumulativeduration that the OLED device has been previously activated, a measuredcurrent, a capacitance, a junction temperature, or a luminance of theOLED device.
 6. The lighting system of claim 1, wherein the controlleris configured to selectively drive at least some of the plurality ofOLED devices at different activation levels such that an output lighthas a desired color characteristic.
 7. The lighting system of claim 6,wherein the controller is configured to selectively drive at least someof the plurality of OLED devices at different activation levels tocompensate for degradation of some of the plurality of OLED devicesthereby maintaining the desired color characteristic of the outputlight.
 8. The lighting system of claim 6, wherein the desired colorcharacteristic is one of a color temperature or a color rendering index.9. The lighting system of claim 1, wherein the controller is configuredto selectively drive at least some of the plurality of OLED devices atdifferent activation levels such that an output light has a desiredintensity and a desired color characteristic.
 10. The lighting system ofclaim 1, wherein the controller is configured to selectively drive atleast some of the plurality of OLED devices at different activationlevels such that an output light has a desired intensity.
 11. Thelighting system of claim 1, further comprising a sensor configured tosense a degradation of at least one of the plurality of OLED devices,wherein the controller is configured to selectively drive at least someof the plurality of OLED devices at different activation levels tocompensate for the sensed degradation.
 12. The lighting system of claim1, further comprising a sensor configured to sense a degradation of atleast one of the plurality of OLED devices, wherein the sensor isconfigured to sense the degradation by measuring one of a temperature, acurrent, a capacitance, or a luminance of at least one of the pluralityof OLED devices.
 13. The lighting system of claim 1, wherein thecontroller is further configured to selectively drive at least some ofthe plurality of OLED devices at different activation levels to improvea lifetime of the lighting system and to have an output light with adesired color characteristic.
 14. The lighting system of claim 1,wherein at least some of the plurality of OLED devices are verticallystacked.
 15. The lighting system of claim 1, wherein at least some ofthe plurality of OLED devices are configured as edge-emitting OLEDdevices.
 16. The lighting system of claim 1, wherein at least some ofthe plurality of OLED devices are vertically stacked, and wherein atleast some of the plurality of OLED devices are substantiallytransparent.
 17. The lighting system of claim 1, wherein the pluralityof OLED devices include a first number of a first type of OLED devicesand a second number of a second type of OLED devices, and wherein thefirst type of OLED devices have a light emission spectrum different froma light emission spectrum of the second type of OLED devices.
 18. Thelighting system of claim 1, wherein the plurality of OLED devicesinclude a first number of a first type of OLED devices and a secondnumber of a second type of OLED devices, and wherein the first type ofOLED devices have a light emission spectrum different from a lightemission spectrum of the second type of OLED devices, wherein the firsttype of OLED devices have an expected lifetime shorter than the secondtype of OLED devices, and wherein the first number is correspondinglylarger than the second number.
 19. The lighting system of claim 1,wherein the plurality of OLED devices include a first number of a firsttype of OLED devices and a second number of a second type of OLEDdevices, wherein the first type of OLED devices have a spectrumdifferent from a spectrum of the second type of OLED devices, whereinthe first type of OLED devices have a lifetime shorter than the secondtype of OLED devices, wherein the first number is correspondingly largerthan the second number, and wherein the controller configured toselectively drive the first type of OLED devices at different activationlevels such that not all of the first type of OLED devices are turned onat the same time thereby increasing the lifetime of the lighting system.20. The lighting system of claim 1, further comprising a mount, whereinat least some of the plurality of OLED devices are configured to beremovably coupled to the mount.
 21. A lighting system comprising: aplurality of organic light emitting diode (OLED) devices, wherein eachof the plurality of OLED devices has an active region, wherein at leastsome of the OLED devices have active regions of different sizes, whereinthe different sizes are selected such that light emitted from thelighting system has desired color characteristics and that the OLEDdevices having active regions of different sizes have substantiallymatching lifetimes, wherein the plurality of OLED devices include afirst type of OLED devices each having an active region of a first sizeand a first expected lifetime, and a second type of OLED devices eachhaving an active region of a second size and a second expected lifetime,wherein a ratio of the first size to the second size is approximatelyproportional to a ratio of the second expected lifetime to the firstexpected lifetime, wherein the first type of OLED devices are driven ata first current density, and the second type of OLED devices are drivenat a second current density, and wherein a ratio of the first currentdensity to the second current density is approximately proportional to aratio of the second size to the first size thereby substantiallymatching actual lifetimes of the first type of OLED devices and thesecond type of OLED devices.
 22. The lighting system of claim 21,wherein the plurality of OLED devices include a first plurality ofactive regions configured to emit substantially red light, a secondplurality of active regions configured to emit substantially greenlight, and a third plurality of active regions configured to emitsubstantially blue light, and wherein at least some of the thirdplurality of active regions have increased sizes and correspondinglyreduced current densities as compared with the first plurality and thesecond plurality of active regions.
 23. The lighting system of claim 21,wherein at least one of the plurality of OLED device comprises: at leastone coupler configured to electrically couple the OLED device to a powersupply; and an encapsulation that isolates the OLED device from anambient environment.
 24. A method comprising: selectively controllingactivation levels of at least some of a plurality of organic lightemitting diode (OLED) devices in a lighting system to improve a lifetimeof the lighting system assigning addresses to the at least some of theplurality of OLED devices; and swapping addresses between at least afirst OLED device and a second OLED device among the at least some ofthe plurality of OLED devices, wherein the first and second OLED deviceshave different wearing levels, and wherein a wearing level of an OLEDdevice is determined based on one or more of an accumulative durationthat the OLED device has been previously activated, a measured current,a capacitance, a junction temperature, or a luminance of the OLEDdevice.
 25. The method of claim 24, further comprising determiningwearing levels of the at least some of the plurality of OLED devices,wherein the selectively controlling activation levels of at least someof the plurality of OLED devices comprises selectively controlling theat least some of the plurality of OLED devices based on the determinedwearing levels of the OLED devices.
 26. The method of claim 24, whereinthe plurality of OLED devices include a first number of blue OLEDdevices, a second number of red OLED devices, and a third number ofgreen OLED devices, wherein the first number is about twice the secondnumber, wherein the selectively controlling activation levels of atleast some of the plurality of OLED devices comprises alternatelyactivating blue OLED devices thereby increasing a lifetime of thelighting system.
 27. A method, comprising: selecting, from a pluralityof pre-manufactured modular organic light emitting diode (OLED) devices,a subset of OLED devices; and coupling the selected subset of OLEDdevices to a mount, wherein the subset of OLED devices is selected tohave a mixed output light spectrum with desired color characteristics,wherein the selecting the subset of OLED devices comprises selecting afirst number of a first type of OLED devices and a second number of asecond type of OLED devices, wherein the first type of OLED devices havea first spectrum different from a second spectrum of the second type ofOLED devices, wherein the first type of OLED devices have an expectedlifetime substantially shorter than an expected lifetime the second typeof OLED devices, and wherein selecting the subset of OLED devicescomprises selecting the first number substantially larger than thesecond number.
 28. The method of claim 27, wherein the selecting thesubset of OLED devices comprises selecting a first number of a firsttype of OLED devices and a second number of a second type of OLEDdevices, and wherein the first type of OLED devices have a firstspectrum different from a second spectrum of the second type of OLEDdevices.
 29. The method of claim 27, further comprising selectivelyactivating the first type of OLED devices such that not all of the firsttype of OLED devices are activated at the same time or at the sameactivation level, thereby increasing the lifetime of the first type ofOLED devices.
 30. The method of claim 27, further comprising selectivelyactivating the first type of OLED devices, wherein selectivelyactivating the first type of OLED devices comprises electrically drivingthe first type of OLED devices with voltage or current pulses shorterthan those of the second type of OLED devices.
 31. The method of claim27, further comprising selectively driving at least some of the subsetof OLED devices with healing current pulses, wherein selectively drivingat least some of the subset of OLED devices with healing current pulsescomprises reversely biasing the devices during part of the currentpulses to heal the devices.
 32. The method of claim 27, furthercomprising selectively driving at least some of the plurality of OLEDdevices to different activation levels to compensate for degradation ofsome of the plurality of OLED devices thereby maintaining the desiredoutput color characteristics.
 33. The method of claim 27, furthercomprising: sensing a degradation of one or more of the plurality ofOLED devices; and driving the one or more of the plurality of OLEDdevices at different activation levels to compensate for the senseddegradation.
 34. The method of claim 27, further comprising: sensing adegradation of one or more of the plurality of OLED devices, wherein atleast some of the plurality of OLED devices are redundant OLED devices;and turning on one or more of the redundant OLED devices to compensatefor the sensed degradation.
 35. The method of claim 27, furthercomprising sensing a degradation of one or more of the plurality of OLEDdevices by measuring one of a temperature, a current, a capacitance, ora luminance of the one or more of the plurality of OLED devices.
 36. Alighting system comprising: a plurality of organic light emitting diode(OLED) devices; and a controller configured to selectively drive atleast some of the plurality of OLED devices at different activationlevels, wherein at least one of the plurality of OLED devices comprises:at least one coupler configured to electrically couple the OLED deviceto a power supply; and an encapsulation that isolates the OLED devicefrom an ambient environment, wherein the plurality of OLED devicesinclude a first number of a first type of OLED devices and a secondnumber of a second type of OLED devices, wherein the first type of OLEDdevices have a light emission spectrum different from a light emissionspectrum of the second type of OLED devices, wherein the first type ofOLED devices have an expected lifetime shorter than the second type ofOLED devices, and wherein the first number is correspondingly largerthan the second number.
 37. A method comprising: selectively controllingactivation levels of at least some of a plurality of organic lightemitting diode (OLED) devices in a lighting system to improve a lifetimeof the lighting system, wherein the plurality of OLED devices include afirst number of blue OLED devices, a second number of red OLED devices,and a third number of green OLED devices, wherein the first number isabout twice the second number, and wherein the selectively controllingactivation levels of at least some of the plurality of OLED devicescomprises alternately activating blue OLED devices thereby increasing alifetime of the lighting system.
 38. A method, comprising: selecting,from a plurality of pre-manufactured modular organic light emittingdiode (OLED) devices, a subset of OLED devices, wherein the subset ofOLED devices is selected to have a mixed output light spectrum withdesired color characteristics; coupling the selected subset of OLEDdevices to a mount; and selectively driving at least some of the subsetof OLED devices with healing current pulses, wherein selectively drivingat least some of the subset of OLED devices with healing current pulsescomprises reversely biasing the devices during part of the currentpulses to heal the devices.
 39. A method, comprising: selecting, from aplurality of pre-manufactured modular organic light emitting diode(OLED) devices, a subset of OLED devices, wherein the subset of OLEDdevices is selected to have a mixed output light spectrum with desiredcolor characteristics; coupling the selected subset of OLED devices to amount; sensing a degradation of one or more of the plurality of OLEDdevices, wherein at least some of the plurality of OLED devices areredundant OLED devices; and turning on one or more of the redundant OLEDdevices to compensate for the sensed degradation.